This invention generally relates to line printers, and more specifically to line printers which are useful for printing successive lines of information on tickets.
Various instruments and other data sources produce information for display as alphabetic or alphanumeric characters by output devices, such as line printers. This invention is particularly applicable to a class of line printers comprising a printing drum in the form of a set of type wheels that rotate in unison on a common shaft intermittently between successive positions. A printing hammer is actuated whenever a comparison circuit indicates that a symbol or character on the type wheel then facing the material to be printed corresponds to the character actually to be printed by that wheel.
These line printers generally print on a roll of paper stored inside a printer housing. When a roll runs out, paper from a new roll is fed into a paper advancing mechanism that feeds the paper past the type wheels. All motion of the paper through the printer is unidirectional, and the paper advancing mechanism is constructed so the paper can be driven or pulled in that same direction with relative ease. Any attempted movement in a reverse direction is met with significant resistance.
These printers are not readily adapted for printing tickets or other short materials. It is desirable in printing a ticket to insert and retrieve the ticket from one slot in the printer. In such a printer the ticket would be fully inserted into the printer and subsequent printing operations would advance the ticket out of the printer or, conversely, the ticket would be inserted to a first position, printed as it was advanced into the printer and then either released for withdrawal or ejected.
Therefore, it is a primary object of this invention to provide a line printer which is adapted for printing on tickets or other material of a short length.
Another object of this invention is to provide a control circuit for a ticket line printer.
Still another object of this invention is to provide a line printer that is simple to design, reliable, of small size and relatively inexpensive to manufacture.